Turnagain Pass RSS

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Sat, March 12th, 2016 - 7:00AM
Sun, March 13th, 2016 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

There is a CONSIDERABLE avalanche hazard today above 1,000′ where upwards of a foot of new snow has fallen with strong winds. A variety of avalanche problems are out there and the one most likely to impact a person are fresh wind slabs 1-2′ thick. These slabs are likely to be triggered by a person and could release naturally with warming by the sun. Additionally, wet loose snow avalanches will be likely on steep sunlit slopes. Cornice falls are possible as well today and glide avalanches continue to release.  

**Today’s message is to go into the backcountry with a conservative mind set. Constantly assess the new snow. How it is sticking (or not sticking) to the old surfaces? Keep in mind that it is springtime and sunshine will be a trigger for avalanches. Safer areas to recreate will be in mellow terrain with slopes less than 35 degrees.

If you are headed to Summit Lake, check out today’s weekly summary HERE.

Special Announcements

Tune-up your avalanche skills for Spring Break, play in the flats and let the snowpack adjust today!  

  • TODAY – Saturday, March 12th join us at Turnagain Pass for a FREE Avalanche Rescue Workshop from 11 am-12:30 pm at the motorized lot. This class is open to everyone. Please bring your beacon, shovel and probe. For more info click  HERE.  Look for the blue CNFAIC Avalanche trailer.

Photo of the set up yesterday at the motorized lot for today’s event:

Sat, March 12th, 2016
Above 2,500'
3 - Considerable
Avalanche risk
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
0 - No Rating
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

A quick hitting storm rolled through the region yesterday bringing a much needed ‘re-fresh’ to Turnagain Pass. The Turnagain Pass SNOTEL station reported 9″ of new snow beginning yesterday around noon and ending last night around midnight. This usually equates to around a foot in the Alpine. The rain/snow line was hovering just under the parking lot elevations on the Pass, around 1,000′. We did get a report of a natural avalanche seen across the Arm from Girdwood, see that and additonal info HERE. This new snow is great news, but a new set of avalanche conditions will come with it as well. These are:

Wind Slabs:  Winds associated with the snowfall were moderate to strong from a generally Easterly direction. This is a perfect recipe for forming wind slabs above treeline that could be anywhere from 1-2+’ thick. How well these fresh slabs are bonding with the old snow surface is uncertain – and something to be wary of today. The old snow surface was quite variable, harboring sun crusts on Southerly aspects, wind crusts and loose faceting snow. All of these surfaces are not likely to promote good bonding right away and our hackles should be up. Things to watch for today:

   1-  Recent avalanches, the skies should clear for good visibility
   2-  Cracking or collapsing in the new snow
   3-  Slopes that have been windloaded – Avoid these today, give them a chance to adjust
   4-  SUN…. If the sun comes out slabs could release naturally with the warming!

Loose Snow Avalanches:  Once the sun does come out (today or tomorrow) damp/wet sluffs are likely to run naturally. These will also be easily triggered by a person. Sluffs should entrain mostly just the new snow, so how much new snow is on a slope will depend on how large the sluff is. 

Cornices:  Another round of snow and wind will only add to the weight of these truck size features overhanging many slopes. Extra caution is warranted when choosing how you travel along ridgelines – give cornices an extra wide berth. Also, limit time under these, they could fall on their own and the sun warming them will add to this possibility.

Avalanche Problem 2
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

AVOID travel under glide cracks. This week has been a particularly active glide avalanche cycle. Glide cracks continue to threaten large areas of terrain throughout Turnagain Pass, Girdwood, and Summit Lake. There were several new glide avalanches seen Wednesday from the Seward Hwy, and a large glide released on the East face of Seattle Ridge a few days ago. Glide cracks are on all aspects within the mid-elevation band (1000′-2500′), and some areas like the SW face of Cornbiscuit and Tincan are covered. This avalanche problem is impossible to predict and is not associated with human triggers. We have been talking about the glide avalanche problem for over two months in the advisory and as long as glide cracks continue to open up, move and release, we will stress the importance of avoiding them

Sat, March 12th, 2016

Yesterday saw a quick moving disturbance move through. Visibility was poor as rain fell below 800-1,000′ with snow above. The Turnagain Pass SNOTEL site has reported 9″ of new snow at 2,000′. Winds associated with the snowfall were 20-25mph from the East along the ridgetops with stronger gusts. Temperatures have been warm, in the mid 30’s F at 1,000′ and the mid 20’sF at 3,500′.

Overnight, snowfall has stopped and winds have died down. For today, skies should begin to clear up as the system exists the region; we are expecting the sun to come out for the afternoon. Winds today are expected to be light, 5-10mph, from a generally East direction and temperatures warm, up to 40F at 1,000′ and the upper 20’sF in the Alpine.  

Sunday and into Monday looks to be mostly clear as well with sunny skies and light Easterly ridgetop winds.

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 31   9   0.9   143  
Summit Lake (1400′) 35   0   0   43  
Alyeska Mid (1700′) 32   5   0.7   110  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24   NE   18   43  
Seattle Ridge (2400′) 26   SE   16   35  
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.